Designers of cargo containers have long faced many related challenges in the design of container sidewalls. First, the structural integrity of the overall container depends on the rigidity and strength of the sidewalls. Second, the sidewalls are optimally light in weight to reduce the transportation costs for the overall container.
Third, government regulations and industry standards often limit the exterior dimensions of cargo containers. Thus, to maximize the capacity of the container, designers of cargo containers seek to minimize the width of the walls of the container without compromising the structural integrity of the container.
Fourth, because cargo containers are repeatedly loaded and unloaded, the interior walls of the container must be resistant to the repeated impact of vehicles and implements used to load and unload the container, and must also optimally be free of protrusions and snag points that could impede the loading or unloading of the container. Fifth, means for securing and dividing cargo within a container are often desirable, and may be provided by incorporating logistics slots in the sidewalls of the container. Other considerations, including the cost and availability of the sidewall components and the ease of manufacturing the sidewalls, are also important.
Composite panel sidewalls have been used in the construction of over-the-road trailers to address many of these challenges. Composite panels are made of a core plastic material and an outer skin of aluminum or steel. The use of composite panels provides many advantages in the construction of trailers. The metal skin of the panels is resistant to damage when the cargo is loaded and unloaded. Also, because of the strength and rigidity of the composite panels, trailer sidewall thickness can generally be reduced as compared to designs that rely on thick structural posts to provide the essential structural rigidity for the trailer. By decreasing the thickness of the walls, an interior width of at least 101 inches can be obtained without exceeding an exterior width of 102.38 inches, the current maximum exterior width under state and federal regulations.
The composite panels are typically joined at their edges with vertical splicer plates on the inside and outside of the trailer, as shown in U.S. Pat. No. 4,904,017 (FIG. 9) issued to Ehrlich, U.S. Pat. No. 5,860,693 (FIG. 2) issued to Ehrlich and U.S. Pat. No. 6,450,564 (FIG. 3) and U.S. Pat. No. 6,578,902 (FIGS. 4 and 5) issued to Sill. The composite panels may also be joined with posts on the inside and outside of the trailer, as disclosed in the applicants' U.S. patent application Ser. No. 11/210,076 filed Aug. 23, 2005 that issued as U.S. Pat. No. 7,152,912, and incorporated herein by reference. These vertical members are typically provided with logistics slots to provide for securing and dividing cargo within the trailer.
Because composite panels provide high strength and rigidity in the construction of the overall trailer, the use of structural posts can be reduced or eliminated. Although the reduction or elimination of such structural posts is generally desirable to reduce the weight of the trailer, these posts have traditionally provided a location for logistics slots where cargo may be secured. Thus, when structural posts are reduced or eliminated through the use of composite panels, the potential locations for logistics slots are also reduced, decreasing the trailer owner's options for securing and dividing cargo within the trailer.
Because composite panel construction and flexibility in the securing and dividing of cargo within the trailer are both highly desirable, a need exists for a composite panel sidewall construction that provides additional logistics slots other than between the edges of adjoining composite panels. Such logistics slots, however, must not create snag points or protrusions on the interior of the trailer. Snag points or protrusions on the inside of the trailer may cause cargo, pallets and loading vehicles to catch on the interior wall of the trailer as cargo is loaded and unloaded, thus creating the potential for damage to cargo and the trailer sidewall. Therefore, it is desirable for the sidewalls of the trailer to be free of snag points and protrusions.
Accordingly, an object of the present invention is to provide a composite panel sidewall construction for a cargo container that provides additional interior logistics slots in the sidewalls of the container for securing cargo loaded into the container.
Yet another object of the present invention is to provide a cargo container with interior walls free of protrusions and snag points that could impede the loading or unloading of the container.
A further object of the present invention is to provide a cargo container with sidewalls of minimum overall thickness to maximize the capacity of the container.
Finally, an object of the present invention is to provide a cargo container sidewall configuration that is economical to manufacture and refined in appearance.